The industrial production of wood frame-like structures, and particularly of rectangular frames for paintings, photographs, mirrors and other items, already uses automated systems and machines which, starting from four strips with both ends cut at 45xc2x0, pick them and place them between four stapling units which are meant to rigidly couple them, at the four corners of the frame, by virtue of appropriate steel staples to be inserted pneumatically astride the joint lines. Furthermore, by virtue of a system of electronically controlled motorized carriages, the mutual position of the stapling units is adapted in each instance to the dimensions of the frames being produced.
The facts summarized above are illustrated and described in detail in U.S. Pat. No. 6,164,512, in the name of the same Applicant as the present invention, which also provides for the use of particular devices that, after picking the four strips from one or more conveyors, by virtue of appropriate translational motions and rotations, would deposit them so as to compose the frame at the four stapling units.
The subsequent practical testing of this machine has allowed to ascertain practically the validity and efficiency of the individual devices and of their combination as well as the high quality level of production. However, careful analysis of the various steps of operation has revealed the need and the possibility to further increase the competitiveness of the machine, significantly increasing hourly production, which is currently penalized by a strip feeding system which is not adequate for the operating speed of the stapling units with which the machine is provided.
Moreover, in the meantime the need has also been felt to complete certain frames, during the assembly of the strips and therefore before joining them by means of the staples, by inserting a transparent plate or a panel of any kind in the appropriately slotted inner edge or, vice versa, by snugly inserting the inner edge of the strips in a corresponding perimetric slot of the panel to be framed.
Accordingly, the aim of the present invention is to provide an automated apparatus which, in addition to significantly reducing the time required to position the strips to be joined and the time required to adapt the machine to changes (even frequent ones) in the format of the frames to be assembled, allows the arrival of all the strips on a single side of the machine, so that any panels or sheets to be combined with the strips can be fed on the opposite side, thus achieving the removal of the finished products from one of the two sides that are perpendicular to the ones used for the two mutually opposite feeds.
Furthermore, since the strips arrive from the cropping unit to the machine in parallel rows and on the same side, this gives an advantage to the strip conveyance system, because it can pick them up from a single cropping unit and because the apparatus can itself be constituted by multiple lines in parallel.
The above aim and other objects which will become better apparent hereinafter, are achieved with an apparatus whose characteristics are defined in the claims. An apparatus according to the invention is advantageously but not exclusively fed, as shown in FIG. 11, by a conveyor which picks the strips prepared by a conventional cropping unit and conveys them toward a machine in accordance to the present invention.
The accompanying drawings clearly show that the strips L, which exit from the cropping unit G and are conveyed by the belt S, pass first on the two-track belt U and then continue on the four-track belt V, which conveys them to the four belts W which act as buffer storage, since each one is long enough to contain at least two strips in a row, and move when the downstream machine requests the strips with which the frame is to be formed in each instance.
By examining FIG. 17 in greater detail it can be noted that the strips standing by on the four buffer belts W are sorted so that there are two short ones in each one of the two intermediate belts and two long ones in each one of the two outer belts. This sorted arrangement is provided by three flaps P: one is arranged above the belt U (FIG. 18) and two are arranged above the belt V (FIG. 19), and said flaps are pivoted vertically to arms which cantilever out onto said belts and are actuated by a corresponding number of actuators Q so that each one can sort the strips in two adjacent tracks.
Obviously, the actuators Q are controlled by an electronic system which, in addition to discriminating the length and the number of the strips, controls the actuation sequence of the flaps P according to the tracks to be fed.